Gysel combiners with high-selectivity filtering characteristics: analysis and design

Abstract This paper provides the details of a novel systematic design methodology for two-way in-phase filtering Gysel splitter/combiner networks with high selectivity, which finds application in high power amplifier modules. It simultaneously realizes a filtering function and a two-way splitter/combiner function. The proposed five-port filtering device, based on the Gysel topology, is transformed into a ring of coupled resonators. A rigorous coupling matrix describing the network is used to synthesize the integrated filtering and combining functions. This general network can be implemented in any of the available filter technologies. In this paper, a few design examples are provided, and a six-pole prototype utilizing compact combline coaxial resonators is demonstrated. The proposed design provides an integrated dual function module, reducing component counts and system complexity. A design was fabricated and tested demonstrating good experimental results.